The present invention relates to mechanical split seals for sealing along a shaft.
Many forms of pumps operate in an environment in which a rotating shaft must be sealed around its periphery to prevent fluids from entering into or exiting from a housing. Split seals comprise a plurality of elements surrounding a shaft rather than one solid annular piece. Replacement may be accomplished without having to slide the seal elements off of the shaft or disassembling other apparatus to permit removal of a solid seal. Split seal elements are simply disassembled and removed from around the shaft. There are typical applications in which replacement of a solid seal could take eight to twenty four hours, while replacement of a split seal might take one hour.
Normally two opposing split seal rings are provided. One is stationary (i.e., non-rotating), and the other rotates. Commonly, two halves each subtending 180.degree. constitute each seal ring. In the form of split seal known as a pusher seal, some movement on the part of the non-rotating seal is permitted. Hydraulic pressure during operation urges the non-rotating seal ring toward the rotating ring. Additionally, biasing means provide spring force to press against the non-rotating seal ring. Hence, two functions must be provided to achieve desired operation. The non-rotating seal ring must be retained to be held in place against the rotating seal ring, and the biasing means must be mounted in a stationary assembly.
In prior art embodiments, a pin is used to retain the non-rotating seal ring with respect to a stationary housing. A slot must be machined into the non-rotating sealing ring centered at a particular circumferential position, and another slot must be machined in the stationary housing that will have to be placed in registration with the slot in the non-rotating sealing ring so that the pin can be inserted to achieve its intended function. One common form of biasing means comprises a plurality of coil springs mounted in an angularly displacement from each other, and each mounted in an axial orientation. Machining for proper mounting of these components must be provided for in the design of the seal assembly. Assembly of the components may be complex. A great deal of manipulation of components may be required. Split seals are often formed by cracking a finished seal ring. Relatively fine grained material will lack the interlocking characteristic of a coarser material. Handling such material without damage to the radially extending surfaces that must mate is difficult. Simplified fixturing means have not customarily been utilized.